It is well known in the golf ball art that numerous dimples are formed on the surface of a golf ball for improving the aerodynamic properties of the golf ball over a golf ball having a dimple-free smooth spherical surface. The provision of dimples is effective for improving the flight performance.
In general, the shape of dimples as viewed from above or in plane is circular. It is also known that the percentage of dimple areas relative to the golf ball surface, referred to as percent dimple area, contributes to flight performance. The higher the percent dimple area, the better become the aerodynamic properties. Accordingly, the use of circular dimples having the same diameter is surpassed by the combined use of dimples of plural types having different diameters. Efforts were made to increase the population of dimples arranged. As a result, not only the circular shape, but also an elliptic shape, a teardrop shape and polygonal shapes such as a hexagonal shape are now available for the shape of dimples as viewed from above.
With respect to the arrangement of dimples, efforts were made to arrange dimples over the spherical surface as evenly as possible. Several spherical polyhedral patterns such as spherical icosahedral, dodecahedral and octahedral patterns have been proposed, as described in JP-A 2000-70413, for example.
However, as long as the arrangement or array of dimples is concerned, a certain limit is imposed on the effect of dimple arrangement independent of how dimples of whatever shape or type are combined. There exists a need for an approach toward an improvement in flight performance of a golf ball based on a concept different from the traditional dimple arrangement.